The visible spectrum ranges from 390 nm to 700 nm. the visible spectrum consist of the red ( 620 - 750 nm ) , orange ( 590 - 620 nm ) , yellow ( 570 - 590 nm ) , green ( 495 - 570 nm ) , blue ( 450 - 495 nm ) and violet ( 380 - 450 nm ) so the wave length 449 nm will produce a violet color
Answer:
B.) a wheel and axle and a lever
Explanation:
P.S - The exact question is -
Given - A wheelbarrow can be used to help lift a load, such as a pile of dirt, and then push the load across a distance. A man pushes a wheelbarrow.
To find - Which simple machines make up a wheelbarrow?
A.) a pulley and an inclined plane
B.) a wheel and axle and a lever
C.) a pulley and a wheel and axle
D.) a lever and a wedge
Proof -
The correct option is - B.) a wheel and axle and a lever
Wheelbarrows are used to carry more goods from place to place by using minimal force as compared when goods are carried by hand.
With this machine, During hauling people can save time.
We would have to search at least 5,000,000,000 (5 billion) stars before we would expect to hear a signal.
To find out the number of stars that we will need to search to find a signal, we need to use the following formula:
- total of stars/civilizations
- 500,000,000,000 (500 billion) stars / 100 civilization = 5,000,000,000 (5 billion)
This shows it is expected to find a civilization every 5 billion stars, and therefore it is necessary to search at least 5 billion stars before hearing a signal from any civilization.
Note: This question is incomplete; here is the complete question.
On average, how many stars would we have to search before we would expect to hear a signal? Assume there are 500 billion stars in the galaxy.
Assuming 100 civilizations existed.
Learn more about stars in: brainly.com/question/2166533
Answer:

Explanation:
Given that,
Mass of a person, m = 84 kg
The person is standing at a top of Mt. Everest at an altitude of 8848 m
We need to find the gravitational potential energy of the person. We know that the gravitational potential energy is possessed due to the position of an object. It is given by :
E = mgh, g is the acceleration due to gravity

So, the gravitational potential energy of the person is 
Answer:
C. a clamp light with a 150-W lightbulb placed 25 cm from the radiometer
Explanation:
because the temperature has to be set, meaning it can't change, and it should be a different distance away than the first one.
Hope this helps! Stay safe!